In certain medical applications, it is desired to supply liquids at two different pressures to an operating instrument. Typical of this is, for example, U.S. Pat. No. 4,019,514, granted to Anton Banko, which is assigned to the assignee of this application, which discloses an instrument for opthamologic surgery. In that patent, two liquid lines are needed, one to supply the instrument with liquid at a first pressure, such as for infusion and a reverse flow liquid which is at pressure higher than the first pressure. Combined with the geometry of the surgical instrument, the higher pressure fluid forces unwanted material to be removed from the surgical site.
Heretofore, this has been accomplished by using two separate containers for the liquid. The container for supplying the higher pressure reverse flow liquid is placed at a higher position than the lower pressure infusion liquid. While such arrangement is operative, it is somewhat cumbersome since two separate liquid containers and two separate liquid lines from the separate liquid containers to the operating instrument must be provided. In addition, it is more difficult to determine the amount of fluid used, since the flow out of two containers must be added. Confirming proper flow from the two containers is also more cumbersome with the previous systems, since two drip chambers, remote from each other, must be observed.